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United States Department of Agriculture

Agricultural Research Service

Title: In Vivo Conversion of Linoleic Acid to Arachidonic Acid in Human Adults

Authors
item Salem, Jr, Norman - NIAAA, NIH, DICBR
item Pawlosky, Robert
item Wefher, Brent - NIAAA, NIH, DICRB
item Hibbeln, Joseph - NIAAA, NIH, DICBR

Submitted to: Prostaglandins Leukotrienes and Essential Fatty Acids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 30, 1999
Publication Date: December 30, 1999
Citation: Salem, Jr, N., Pawlosky, R.J., Wefher, B., Hibbeln, J. 1999. In vivo conversion of linoleic acid to arachidonic acid in human adults. Prostaglandins Leukotrienes and Essential Fatty Acids. 60(5&6):407-410

Interpretive Summary: It is shown that human adults carry out essential fatty acid metabolism in vivo using stable isotopes. They are shown to convert linoleic acid to arachidonic acid. It is also confirmed that they can convert linolenic acid to eicosapentaenoic acid and to docosahexaenoic acid. The time course for these processes during the first week after a single oral dose of linoleic acid and linolenic acid is described. A stable-isotope method employing gas chromatography/mass spectrometry analysis is used in order to provided high sensitivity and selectivity of detection. This research will be used by people who study human nutrition to better understand the importance of fats in our diets.

Technical Abstract: This report describes the development of a robust method for studying the metabolism of B-carotene-d8 in humans using a combination of liquid chromatography/ particle-beam-mass spectrometry (LC/PB-MS). The utility of the LC/PB-MS method was demonstrated in a pilot study. The carotenoids were extracted from plasma into hexane and separated by reverse phase high-performance liquid chromatography (HPLC) using a C-18 column. The HPLC solvent was removed under vacuum within the dual-stage particle-beam interface. The de- solvated carotenoids were ionized in the negative-ion mode using methane chemical ionization and detected using selected ion monitoring. The limit of detection of the method was on the order of 0.3 ng (approximately 0.6 pmol) for B-carotene. B-Carotene-d8 was quantified in the plasma over a concentration range of two orders of magnitude using B-carotene-13C40 as an internal standard. The overall coefficient of variance (CV) for determining the concentration of the analytes from 30 ul of plasma was 3.9% for b-carotene and 2.4% for B-carotene-d8. The simplified experimental design having both high sensitivity and a high sample through-put makes large comprehensive studies feasible.

Last Modified: 7/23/2014